The present invention relates to a device according to the preamble of claim 1 to be placed on or integrated into offboard surfaces, for example barges onto which a ship operator has the intention to discharge cargo over a ramp.
Until today, the problem of discharging heavy rolling or tracked cargo from RoRo-ships instream onto barges has mainly been solved by seeking sheltered anchored locations where the effects of waves and swell are dampened by protecting land. The ship""s ramp has been put down on the barges, sometimes with a wooden dunnage between the ramp foot and the barge deck, and the cargo has been discharged from the ship to the barge(s) over the ramp.
On open coasts it has until now only been possible to carry out offloading operations when wind and waves have been fair and light.
Experience has shown that present offloading arrangements for RoRo-ships discharging to barges have had a practical limit at a very calm seastate. When wind, waves and swell has increased, twisting and heaving of the stern ramp has forced operations to stop. Around the coasts of the world, the necessary seastate or less is only prevailing in less than 8% of the total available time.
The object of the present invention is to reduce the torsion loads imposed on the ramp emanating from the relative movements between a ship and offboard surfaces, such as barges, caused by the waves and swell of the sea thus effectively enlarging the available time-window for operation. The present invention will reduce the torsional loads imposed on the RoRo-ramp from the offboard surfaces, which as barges thereby making discharging operations for tracked and wheeled vehicles possible up to higher seastate. Thus the timewindow when operations are possible will increase from todays 8% to 30% or more.
Said object is achieved by means of the device according to the present invention, which is characterised according to claim 1.
The necessary reduction of the torsional loads induced in the ramp structure by the barge movements is achieved by means of a movable platform/deck on which the ramp foot shall be placed. Said platform is to be equipped with pivoting means along at least one axis.
If necessary, the platform can be resting in hingecups on a second frame, which is equipped with second pivoting means having their axis essentially perpendicularly to the first axis.
This second pair of hinges is resting in hingecups supported from the barge""s deck. The level variations between the pivoting platform and the deck of the barges are taken up by fingerflaps attached to the platform and resting on the deck of the barge.